The effects of lithium in emotionally disturbed children having at least one manic-depressive lithium responsive parent will be examined. Thirty children, ages, 5-15, of both sexes, having psychiatric symptoms that are in some way incapacitating and are of major concern to the child, parent, or teacher will be selected. Children will be given lithium and placebo, in a double-blind, crossover design for 16 weeks. Behavior ratings will include: parent's and teacher's assessment, psychophysiological measures, child interview, and cognitive testing. The lithium administration will be monitored by an "unblind" co-investigator.